The present invention relates to a method for manufacturing plastic-substitute goods by using natural materials. Particularly, the invention relates to a method for manufacturing plastic-substitute goods by using natural materials, in which agricultural byproducts and wood byproducts such as rice husks, rice plant stems, corn plant stems, bean plant stems, wheat plant stems, saw dust and the like and the washed and dried sludge produced from the alcoholic factory are crushed into a particular size, then the crushed particles are mixed with natural adhesives (such as corn starch, potato starch and the like), and are coated with melamine resins or urea resins, and then a molding is carried out by applying a pressure in a molding machine, thereby manufacturing the natural plastic-substitute goods.
There are various everyday goods which are made of plastic materials. Further, their shape and use are diversified, and have been continuously developed. However, the plastic materials are highly combustible, and therefore, in case of a fire accident, they are speedily burned off without allowing the fire fighting time. Further, when they are burned, toxic gases are generated to sacrifice human lives. When they are discarded, they are not decomposed, with the result that the natural environment is contaminated.
The present invention is intended to overcome the above described disadvantages of the conventional practice.
Therefore it is an object of the present invention to provide a method for manufacturing plastic-substitute goods by using natural materials, in which one or more materials are selected from among agricultural byproducts and wood byproducts such as rice husks, rice plant stems, corn plant stems, bean plant stems, wheat plant stems, saw dust and the like and and the dried sludge produced from the alcoholic factory, then they are washed, sorted and dried, then they are mixed with natural adhesives such as corn starch, potato starch and the like, then they are dried and crushed, then they are mixed with a coating material such as melamine resins or urea resins, and then, they are press-molded in a molding machine.
The agricultural byproducts and the wood byproducts can be selectively used, and the rice husks, rice plant stems and other plant byproducts can be mixedly used.
As the natural adhesive, there can be used corn starch and potato starch, but other cereal powder may be used to reap the same effect. Corn starch and potato starch are preferred because they are cheap. The substitute materials are crude in their touching sense and in the color, and therefore, they can be dyed.
Melamine resin or urea resin is a thermosetting resin which is formed by reaction of melamine or urea acting upon formaldehyde. A first mixture is produced by mixing formaldehyde solution 30 wt % and water 70 wt %. A second mixture is then achieved by mixing the first mixture at 70 wt % with melamine or urea 30 wt % and heating the result at a temperature of 350 degrees Centigrade. Then the resulting substance is mixed at 60 wt % with cellulose powder 40 w %. After drying and powdering this outcome, melamine resin or urea resin is obtained. The alkaline attribute of the formaldehyde liquid has a poisonous character, which is eliminated by heating at a high temperature after mixing in the melamine or urea.
Said melamine resin and urea resin are generally called amino plastic because they have xe2x80x94NH2, the amino radical. These resins are colorless, transparent, easily colored, water-resisting and thermostable.
Further, when molding the product of the present invention, the product can be easily separated from the molding die owing to the presence of melamine resin or urea resin, and therefore, the melamine or urea resin facilitating molding, separating and water-resisting of receptacle is an important element in the present invention. In the present invention, the molding is carried out at a temperature of 100-350 degrees C., the internal pressure is preferably 5 Kg/Cm2, and the molding speed is 30-80 seconds per product.
The agricultural byproducts, the wood byproducts and other plant byproducts are mostly waste materials, and therefore, can be easily obtained. However, their availabilities are affected by seasons, and therefore, the most readily available materials in the season can be selectively used.